New research from Brown University reinforces the idea that grooves crisscrossing the surface of Phobos, the larger of the two Martian moons, were made by rolling boulders blasted free from a huge asteroid impact. Martian moon Phobos. Image credit: NASA / JPL-Caltech / University of Arizona. Phobos’ grooves, which are visible across most of the moon’s surface, were first glimpsed in the 1970s by NASA’s Mariner and Viking missions. Over the years,...
